Door Arm Rest Week 8 Challenge

Title: Creation of Door Arm rest

Aim:

• To create the door arm rest component using the given class A surface of the arm rest and door.

Objectives:

• To create class B and C surface from given class A surface

• To make solid closed body model using class C surface

• To perform draft analysis for class A surface and solid body w.r.t tooling axis and side core axis.

• To publish class A,B,C surfaces, Tooling axis and side core axis.

Introduction:

•  This report demonstrate the design of door arm rest  an automotive plastic component with industry principle like determine and implementation of tooling axis, side core axis, draft analysis, draft angle, creation of class B and C surfaces and maintain thickness of part at 2.5 mm. The plastic component is designed with surface and part design technique in CATIA.

Methodology:

Fig. 1 Methodology for designing of door arm rest

Some term are defined before designing:

Class A surface:

• A surface is made by designer and surface design is given to modeler to work on it.

• It is aesthetic surface and the outer most surface of any automotive component. 

• Class A surface is refers to those surfaces which are visible and abide to the physical meaning in a product. this classification is primarily used in any automotive and increasingly in consumer goods industry.

• That`s why exterior of automobiles is deemed is class A surface.

 Class B Surface:

• A surface which is below a certain thickness from class A surface is called as class B surface. It contains engineering aspects of a model.

• it is generally visible from back side of class a surface.

• Class B surface is designed as per class A surface. i.e the continuity, thickness of component, functionality etc. should be maintained.

 Class C Surface:

• A class C surface that join class- A and Class B surface along tooling axis.

• It contains draft as per design..

• It is basically thickened surface between class A & B surface.

 Tooling axis:

• It is a direction in which mold / core and cavity opens.

• Analyze model visually to see which direction is most suitable for tooling axis and draft analysis is done along tooling axis.

 Side Core axis:

• some walls are difficult to clear through tooling axis itself. These features may have negative draft angle which cannot be ignored, so they need a different tooling direction for clearing the part in the mold. Such type of tooling direction called as side core axis.

 Draft:

• It is an angular tapering given in the direction of mold movement at design stage to every plastic components that has to be manufactured. The draft allows the part to release easily from the mold without creating friction between the surface of component and core- cavity plates. In most application require minimum draft angle of around 0.5 to 1°, however 3° draft angle is widely accepted for cost saving purpose.

 Draft Analysis:

• It is a tool in CATIA which analyze and identifies zones which are deviates from specified angle value along specified draft direction using color codes.

step-1 :- Input surfaces:

• Below fig. 2 shows input received from designer. Pink color part is side door and blue color part is plastic arm rest.

Fig. 2. Given Input door arm rest and door

Fig. 3 Door arm rest component in Isometric view

Step- 2 Design check (Pre-check) of input given door arm rest:

• After receiving class A surface/ door arm rest shown in fig.3 , check the connectivity of surfaces.

• First important thing is to check continuity of given class A surface i.e to ensure that class A surface is properly joined or there is no discontinuity in the model. This can be checked by using two options, Join or Boundary feature in CATIA. 3 shows connectivity of class A surfaces.

Step-3 Determine the tooling axis:

• Identify the surfaces which can creates problem while manufacturing with all 3 axes.

• After analyzing tooling direction of class A surface, it found that there is need of two tooling direction/ axis.

• Here we have created dummy tooling axis before creation of main tooling axis.

Following procedure is used to create dummy tooling axis:

• A Base surface of class A surface is extracted and untrimmed it shown in Fig. 4

• Create a point on the surface at center using point command, shown in Fig. 5

• Generated a line along Z-direction using point- direction command shown in Fig. 6. And this line is dummy tooling axis for reference.

• For draft analysis along z- axis will not cleared all surface, hence need of main tooling axis.

• New axis system is inserted at point, shown in fig.7

Fig.4 base surface is extracted & untrimmed

Fig.5 Point is created on surface

Fig.6 Line is created with the point

Fig.7 Axis system is inserted

1.Tooling Axis in Y direction:

• Create a position sketch on ZX plane and use intersect 3D.

• Draw line on inclined surfaces and take bisection of both line, this is tooling axis in y direction.

Fig.8 Tooling axis in Y direction

2.Tooling Axis in X direction-

• Create a position sketch on YZ plane and use intersect 3D.

• Draw line on inclined surfaces and form center at an angle of 4°.

• Take bisection of both line, this is tooling axis in X direction.

Fig.9 Tooling axis in X direction

3.Main Tooling Axis:

• Bisect both the tooling axis in X and Y direction to get main tooling axis, shown in Fig.10

• fig.11 shows arm rest surfaces are not cleared along created tooling axis. so there is need to create new tooling axis.

• Perform the draft analysis through the created line on the arm rest component.

• If all wall clearance is not achieved, orient the compass as per requirement.

• When all rest arm surfaces are turned into green color/ clearance is achieved, lock the compass orientation.

• Now edit the line definition, use point direction method in which use created point and direction to the compass direction.

• This is our main tooling axis (Red in color) for arm rest component shown in fig.12.

Fig. 10 Line created using tooling axis in X and Y direction

 Step- 4 Draft Analysis along tooling axis

• To perform draft analysis on class A surface go to- Insert > Analysis > Feature Draft Analysis.

• Then perform draft analysis on each tooling axis. Make sure that before switching to draft analysis part should be in customer view parameter with material option of mesh. Next step is to align the tooling axis with class A surface by clicking on compass icon and drag it to tooling axis. After clicking on surface we get tab and it shows different color scales with different draft angle range. The minimum draft angle is 3°. From fig. 11we can see that red color shows 0° of draft angle, green color is above 0° and blue color is below 0°. So try to keep draft angle positive.

Fig.11 Draft analysis along Main tooling axis.

Step-5 Side core axis:

• To clear the bin wall a side tooling along y direction can be considered as a possibility.

• To create, pocket surface is extracted and untrimmed it fig. 12.

• Create a line along a surface untrimmed through a point which is created for dummy tolling axis is shown in fig. 13

• Perform the same think to left side wall and create a line.

• Then create a bisecting line with the two lines….

• Perform the draft analysis through the bisecting line is shown in fig. 14.

• If clearance is not achieved, orient the compass as per requirement.

• When all bin surfaces are turned into green color/ clearance is achieved, lock the compass orientation.

• Now edit the line direction to the compass direction.

• This is our final side core axis for bin wall.

Fig. 12 Pocket surface & wall  is extracted

Fig. 13 Line along untrimmed surfaces

Fig.14 Creating of bisecting line

Step- 6 Draft Analysis for side core:

• Follow the same procedure used for draft analysis along tooling axis.

Fig. 15 Draft analysis of side core along created line

Step-7 Creation of class B Surface:

• First, extract all the surfaces for the inclined portion of the base plate.

• Then these surface are first untrimmed to get the intersection for surfaces so that a replica can be created.

• If the surface are not intersected, then extrapolate by point continuity propagation is used to make these surface have an intersection between them.

• Lastly, the surface trim is used to get the replica for the inclined surface.

• Now, the thickness of the final component is 2.5mm so this obtained surface is offset below by 2.5mm.

• Like that the rest of the region is extracted and trimmed to get the final B surface.

• Now, the fillets assigned in the B class surface will be inside fillet 17-2.5mm(Thickness) = 14.5mm and outside fillet 17+2.5mm=19.5mm. This is to have the uniform thickness between the A and B classes.

• The whole component B surface is created in small parts, then joined using the trimmed option and then the final fillets are assigned.

Step- 8 Creation of Class C surface:

• C Class is where the thickness of the component can be seen.

• The process for C Class surface is as follows:

• The C class surface will be created using the sweep command and for that, the boundary lines are obtained from the A class surface.

• The curve part is then smooth by some value for ease in sweeping.

• Then, all boundary lines are sweep with draft direction since all surfaces must have a draft angle of 3 degrees and sometimes we use 87deg for vertical faces & in some faces we use multi section surface. Also, the tooling axis is used as the direction of the sweep.

Next, the surface are joined with the A class to form a complete A and C surface.(note merging distance is kept at 0.003mm to avoid any gaps).

Lastly, the A and C is trimmed with the B surface to get the final surface component.

Step- 9 Publication:

• This feature is used to make easy access of published component (Surface or Sketch).

• Here class A,B,C surface, tooling axis and side core axis is published.

• Path- Tools > Publication > Select entity (Surface/ Sketch/Body)

step-10 Creation of solid body:

• Solid body is created using class C surface.

Step 11- Draft Analysis on Class A surface and arm rest Solid body:

Screenshots of the class A surface along tooling axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

Screenshots of the solid body model along tooling axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

Screenshots of the class A surface model along Side core axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

Screenshots of the solid body model along Side core axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

Screenshots of the solid model in various orientations (Isometric, Front, Side, and Top View)

Screenshots of the Surface model in various orientations (Isometric, Front, Side, and Top View)

Conclusion:

• The tooling axis and side core axis are identified and created for class A surface.

• The class B and C surface are created from given class A surface in CATIA V5.

• The solid closed body model is made using class C surface.

• Draft analysis is performed for class A surface and solid body w.r.t tooling axis and side core axis.

• To publish class A,B,C surfaces, Tooling axis and side core axis.